[SOLVED] Low-level JTAG: setting JLink TMS, TCK, TDI high/low

I need to work with low-level JTAG. I've seen the the JTAGLoad facility, for SVF tests, but what I need is the ability to see what is shifted out of TDO (when this is unknown), not just test if it equals an expected output.

With what tools can I set the pins of the JLink (TMS, TCK, and TDI) to high or low and then view the resulting output on TDO? Or, what setup should I use? Is there a way to do this in Eclipse?

Thank you for your inquiry.
For this purpose you can write J-Link Scriptfile and use the Script file API function described on the J-Link user manual.
e.g. JLINK_PIN_Override to toggle individual pins or JLINK_JTAG_Write to write a whole JTAG sequence.